Association of Maternal Stress and Social Support During Pregnancy With Growth Marks in Children's Primary Tooth Enamel

Can social adversity alter the epigenome, trigger oral disease, and affect future generations?

The nature versus nurture debate has intrigued scientific circles for decades. Although extensive research has established a clear relationship between genetics and disease development, recent evidence has highlighted the insufficiency of attributing adverse health outcomes to genetic factors alone. In fact, it has been suggested that environmental influences, such as socioeconomic position (SEP), may play a much larger role in the development of disease than previously thought, with extensive research suggesting that low SEP is associated with adverse health conditions. In relation to oral health, a higher prevalence of caries (tooth decay) exists among those of low SEP. Although little is known about the biological mechanisms underlying this relationship, epigenetic modifications resulting from environmental influences have been suggested to play an important role. This review explores the intersection of health inequalities and epigenetics, the role of early-life social adversity and its long-term epigenetic impacts, and how those living within the lower hierarchies of the socioeconomic pyramid are indeed at higher risk of developing diseases, particularly in relation to oral health. A deeper understanding of these mechanisms could lead to the development of targeted interventions for individuals of low SEP to improve oral health or identify those who are at higher risk of developing oral disease.

How well do parents identify their child's baby teeth? Engagement and accuracy of parent-reported information on a tooth checklist survey

OBJECTIVES

Naturally exfoliated primary teeth are being increasingly collected in child development studies. Most of these odontological collections and tooth biobanks use parent-reported information from questionnaires or tooth checklists to collect data on offspring teeth. To the best of the authors' knowledge, no studies have assessed parental engagement in tooth checklists, nor parental accuracy in identifying their child's baby tooth. This study aimed to evaluate these dimensions by analysing data from the about this tooth checklist returned with donated primary teeth in a natural experimental study called STRONG (the Stories Teeth Record of Newborn Growth).

METHODS

Parental self-reported information were analysed on checklists returned with 825 primary teeth belonging to 199 children. The percentage of blank answers was calculated for each question. The accuracy of parents-reported tooth identification was evaluated by comparing parental ratings to researchers' ratings. Reliability of researchers' tooth identification was first evaluated by calculating intra-observer and inter-observer agreements, as well as Cohen's Kappa values. The percentage of accuracy of parents' tooth identification (relative to researcher's) was then calculated, and logistic regressions were used to evaluate if time elapsed between when exfoliation occurred and the checklist was completed associated with parental accuracy in tooth identification.

RESULTS

Parents returned 98.4% of the checklists and completed 74.9% to 97.7% of the questions. Excellent reliability was demonstrated for researchers' intra- and inter-rater tooth identification (agreement percentages >90%; Cohen's Kappa values >.83). Moderate accuracy of parents-reported tooth identifications was found, with parents correctly identifying 49.5% of the donated tooth. Better parental accuracies were highlighted for partial identifications (87.1% of correct jaw, 75.6% of correct tooth type, and 65.8% of correct lateralization). Logistic regressions showed the odds of correct parental identifications decreased on average by 1.8% every 30 days of distance between tooth exfoliation and checklist completion.

CONCLUSIONS

While parental engagement is high, parents-reported tooth identifications have moderate accuracy, which decreases over time. High accuracy is however found for partial identifications. Parent-reported information on the accompanying questionnaire of naturally exfoliated primary teeth collection or tooth biobanks, even when filled in a long time after exfoliation took place, should be encouraged. However, expert identifications of teeth should remain best practice.

Cultural diversity of traditions for the disposal of exfoliated teeth: Implications for researchers

OBJECTIVES

For decades, researchers in anthropology and archaeology have used teeth, including exfoliated primary teeth, as fossil records of people's physical life experiences. Recently, researchers in psychiatry, epidemiology, environmental health and other fields have recognized the potential for teeth to serve as biomarkers of other early-life experiences, including trauma exposure and other types of psychosocial stress, which are potent determinants of later mental and physical health problems. Despite the emerging appreciation and value of teeth as biospecimens, little is understood about cultural beliefs and practices surrounding exfoliated teeth. If known, such insights could inform culturally appropriate practices for paediatric dental care and improve protocols for the ethical acquisition of teeth as biospecimens in research studies. To address this gap, a qualitative systematic review was performed to summarize the variety of traditions performed worldwide for disposing of primary exfoliated teeth.

METHODS

PubMed, Google Scholar, AnthroSource, Anthropological Literature, EHRAF World Cultures and Anthropology Plus were searched with a systematic search strategy to identify articles published from inception through December 2, 2021. Citations of relevant papers were also forward and backward searched.

RESULTS

There were 3289 articles that met the initial inclusion criteria, of which 37 were included after individual screening and applying exclusion criteria. Thematic analysis was used to identify 74 distinct traditions related to the disposal of exfoliated teeth, which were organized into seven general themes: (1) giving teeth to a tooth fairy, (2) giving teeth to mouse figures, (3) throwing teeth, (4) hiding/keeping teeth, (5) burying teeth, (6) giving teeth to animals and (7) eating the tooth.

CONCLUSIONS

The results of this study elucidate the diversity within-yet universality of-exfoliated tooth disposal traditions and underscore the importance of tooth exfoliation as a major milestone during child development. Special attention must be paid to these traditions and related ethical concerns when designing research protocols related to their collection. With a greater understanding of beliefs and practices related to exfoliated teeth, researchers will be better equipped to engage children and families in studies that include analyses of exfoliated teeth, collect teeth as biospecimens, and broaden the use of teeth in research.

Prenatal Stress and the Developing Brain: Postnatal Environments Promoting Resilience

Heightened maternal stress during pregnancy is associated with atypical brain development and an elevated risk for psychopathology in offspring. Supportive environments during early postnatal life may promote brain development and reverse atypical developmental trajectories induced by prenatal stress. We reviewed studies focused on the role of key early environmental factors in moderating associations between prenatal stress exposure and infant brain and neurocognitive outcomes. Specifically, we focused on the associations between parental caregiving quality, environmental enrichment, social support, and socioeconomic status with infant brain and neurocognitive outcomes. We examined the evidence that these factors may moderate the effects of prenatal stress on the developing brain. Complementing findings from translational models, human research suggests that high-quality early postnatal environments are associated with indices of infant neurodevelopment that have also been associated with prenatal stress, such as hippocampal volume and frontolimbic connectivity. Human studies also suggest that maternal sensitivity and higher socioeconomic status may attenuate the effects of prenatal stress on established neurocognitive and neuroendocrine mediators of risk for psychopathology, such as hypothalamic-pituitary-adrenal axis functioning. Biological pathways that may underlie the effects of positive early environments on the infant brain, including the epigenome, oxytocin, and inflammation, are also discussed. Future research in humans should examine resilience-promoting processes in relation to infant brain development using large sample sizes and longitudinal designs. The findings from this review could be incorporated into clinical models of risk and resilience during the perinatal period and used to design more effective early programs that reduce risk for psychopathology.

Sensitive periods in development and risk for psychiatric disorders and related endpoints: a systematic review of child maltreatment findings

Variation in the mental health of people who have experienced childhood maltreatment is substantial. One hypothesis is that this variation is attributable, in part, to the timing of maltreatment-specifically, whether maltreatment occurs during sensitive periods in development when the brain is maximally sensitive to particular types of environmental input. To determine whether there is scientific consensus around when periods of peak sensitivity occur, we did a systematic review of human observational studies. Although 89 (75%) of the 118 unique cross-sectional or longitudinal cohort studies we identified reported timing effects, no consistent sensitive periods were identified for any of the most studied outcomes. Thus, observational research on childhood maltreatment has yet to converge on a single period (or set of periods) of increased vulnerability. We identified study characteristics that might contribute to these between-study differences and used observations from our Review to suggest a comprehensive set of recommendations for future research.

Social Epigenomics: Conceptualizations and Considerations for Oral Health

Advances in high-throughput technologies and the generation of multiomics, such as genomic, epigenomic, transcriptomic, and metabolomic data, are paving the way for the biological risk stratification and prediction of oral diseases. When integrated with electronic health records, survey, census, and/or epidemiologic data, multiomics are anticipated to facilitate data-driven precision oral health, or the delivery of the right oral health intervention to the right individuals/populations at the right time. Meanwhile, multiomics may be modified by a multitude of social exposures, cumulatively along the life course and at various time points from conception onward, also referred to as the socio-exposome. For example, adverse exposures, such as precarious social and living conditions and related psychosocial stress among others, have been linked to specific genes being switched "on and off" through epigenetic mechanisms. These in turn are associated with various health conditions in different age groups and populations. This article argues that considering the impact of the socio-exposome in the biological profiling for precision oral health applications is necessary to ensure that definitions of biological risk do not override social ones. To facilitate the uptake of the socio-exposome in multiomics oral health studies and subsequent interventions, 3 pertinent facets are discussed. First, a summary of the epigenetic landscape of oral health is presented. Next, findings from the nondental literature are drawn on to elaborate the pathways and mechanisms that link the socio-exposome with gene expression-or the biological embedding of social experiences through epigenetics. Then, methodological considerations for implementing social epigenomics into oral health research are highlighted, with emphasis on the implications for study design and interpretation. The article concludes by shedding light on some of the current and prospective opportunities for social epigenomics research applied to the study of life course oral epidemiology.

Association Between Measures Derived From Children's Primary Exfoliated Teeth and Psychopathology Symptoms: Results From a Community-Based Study

Mental disorders are among the most disabling health conditions globally. However, there remains a lack of valid, reliable, noninvasive, and inexpensive biomarkers to identify (at an early age) people who are at the greatest risk of experiencing a future mental health condition. Exfoliated primary teeth, when used in combination with established and emerging tools (e.g., family history, imaging, genetics, epigenetics), may provide important additional insights about vulnerability to mental illness. Teeth are especially promising because they develop in parallel with the brain and maintain a permanent record of environmental insults occurring during prenatal and perinatal development. Despite their potential, few empirical studies have investigated features of exfoliated teeth in relation to mental health. Here, we used micro-CT imaging to test the hypothesis that measures derived from exfoliated primary incisors associated with psychopathology symptoms in a community-based sample of children (n = 37). We found that enamel volume (β = −0.77, 95% CI, −1.35 to −0.18, P = 0.01) had large negative associations with internalizing symptoms, and enamel mineral density (β = 0.77, 95% CI, 0.18–1.35, P = 0.01) had large positive associations with internalizing behavioral symptoms, even after stringent control for multiple testing. Pulp volume (β = −0.50, 95% CI, −0.90 to −0.09, P = 0.02) had a moderately-large negative association with externalizing behavioral symptoms, though these associations did not survive multiple testing correction. These results support the ongoing investigation of teeth as potential novel biomarkers of mental health risk.

Protocol for a Case Control Study to Evaluate Oral Health as a Biomarker of Child Exposure to Adverse Psychosocial Experiences

Background: The early identification of children who have experienced adversity is critical for the timely delivery of interventions to improve coping and reduce negative consequences. Self-report is the usual practice for identifying children with exposure to adversity. However, physiological characteristics that signal the presence of disease or other exposures may provide a more objective identification strategy. This protocol describes a case–control study that assesses whether exposure to adversity is more common in children with tooth enamel anomalies compared to children without such anomalies. Methods: For 150 mother–child pairs from a pediatric dental clinic in Toronto, Canada, maternal interviews will assess the child’s adverse and resilience-building experiences. Per child, one (exfoliated or extracted) tooth will be assessed for suspected enamel anomalies. If anomalies are present, the child is a case, and if absent, the child is a control. Tooth assessment modalities will include usual practice for dental exams (visual assessment) and modalities with greater sensitivity to identify anomalies. Conclusion: If structural changes in children’s teeth are associated with exposure to adversity, routine dental exams could provide an opportunity to screen children for experiences of adversity. Affected children could be referred for follow-up.

How prenatal environmental factors affect rat molar enamel formation?

Amelogenin (AMELX) and ameloblastin (AMBN) are crucial for enamel formation, and interruptions in the production of these proteins may cause enamel defects. We investigated how prenatal environmental factors (chronic stress, bisphenol A (BPA), amoxicillin, and lipopolysaccharide (LPS)) affect AMELX and AMBN production of ameloblasts. Fifteen pregnant Sprague-Dawley rats were divided into four experimental groups and a control group. Chronic-stress group rats were exposed to a 12:12 light/light cycle (LL) from day E18 until delivery. BPA group rats were orally administered 5 μg/kg BPA daily from day E1 until delivery. Amoxicillin group rats were injected 100 mg/kg amoxicillin daily from day E18 until delivery. LPS-infection group rats were injected 125 μg/kg bacterial LPS once on day E18. Seven pups from the control group and ten pups from the experimental groups were euthanized on P10. Sections were stained with hematoxylin and eosin (H&E) and Gomori's one-step trichrome staining (GT) and incubated with rabbit polyclonal antibodies to AMELX and AMBN, to evaluate staining intensity at ameloblast stages. The surface morphology was evaluated with a stereomicroscope. AMELX (p = 0.008, p = 0.0001, p = 0.009) and AMBN (p = 0.002, p = 0.001, p = 0.0001) staining of all groups were significantly lower than that of the control group in the secretory, transitional, and maturation stages. Abnormal enamel matrix formation was observed in the H&E and GT staining sections of all experimental groups. Yellowish coloration of the amoxicillin group was observed in morphologic evaluation.

A growth area: A review of the value of clinical studies of child growth for palaeopathology

Studies of living children demonstrate that early life stress impacts linear growth outcomes. Stresses affecting linear growth may also impact later life health outcomes, including increased cardiometabolic disease risk. Palaeopathologists also assess the growth of children recovered from bioarchaeological contexts. Early life stresses are inferred to affect linear growth outcomes, and measurements of skeletal linear dimensions alongside other bioarchaeological information may indicate the types of challenges faced by past groups. In clinical settings, the impacts of stress on growing children are typically measured by examining height. Palaeopathologists are limited to examining bone dimensions directly and must grapple with incomplete pictures of childhood experiences that may affect growth. Palaeopathologists may use clinical growth studies to inform observations among past children; however, there may be issues with this approach. Here, we review the relationship between contemporary and palaeopathological studies of child and adolescent growth. We identify approaches to help bridge the gap between palaeopathological and biomedical growth studies. We advocate for: the creation of bone-specific growth reference information using medical imaging and greater examination of limb proportions; the inclusion of children from different global regions and life circumstances in contemporary bone growth studies; and greater collaboration and dialogue between palaeopathologists and clinicians as new studies are designed to assess linear growth past and present. We advocate for building stronger bridges between these fields to improve interpretations of growth patterns across human history and to potentially improve interventions for children living and growing today.